3-cycloalkylthio-3-azabicyclo (3.2.2) nonanes

ABSTRACT

Compounds of the formula WHEREIN N IS 2 TO 9 WHICH ARE STABILIZERS OF ORGANIC COMPOUNDS AND INHIBITORS OF PREMATURE VULCANIZATION.

Unite States Patent DAmico [54] 3-CYCLOALKYLTHIO-Ii-AZABICYCLO (3.2.2) NONANES [62] Division of Ser. No. 17,970, March 9, 1970,

Pat. No. 3,627,738.

52 us. Cl ..260/239 BA 51 Int Cl. .,....C07d 41/04 58 Field of Search ..260/239 BA [56] References Cited OTHER PUBLICATIONS D Arnico et al., ChemsAbstracts, v01. 69, Abstract No. 36009y (1968). QDiASl.

[15] 3,692,770 [451 Sept. 19,1972

Primary Examiner-Alton D. Rollins Anorney--Richard O. Zerbe et al.

[57] ABSTRACT Compounds of the formula s Nsofi C112)" wherein n is 2 to 9 which are stabilizers of organic compounds and inhibitors of premature vulcanization.

4 Claims, No Drawings 3-CYCLOALKYLTHIO-3-AZABICYCLO (3.2.2) NONANES SUMMARY OF THE INVENTION.

The sulfenamides of this invention have the formula ig: 3 N s CH H2) n where n is an integer from 2 to 9. They may be prepared by reacting a cycloalkylthio halide with 3- azabicyclo[3.2.2]nonane. Examples of suitable cycloalkyl radicals are cyclopentyl, cyclohexyl, cyclooctyl, cyclodecyl and cyclododecyl.

The new compounds inhibit premature vulcanization or scorch of vuicanizable rubber compositions and activate vulcanization at curing temperatures. This means that rubber stocks containing the inhibitors cure faster yet have greater processing safety. The inhibitor activity is supported by the presence of the cycloalkyl radical. Replacement of the cycloalkyl radical with an aryl radical gives compounds with entirely different properties.

The inhibitors of my invention may be used in natural and synthetic rubbers. Synthetic rubbers that may be improved by the process of this invention include cis-4-polybutadiene, butyl rubber, ethylenepropylene terpolymer rubber, polymers of 1,3-butadiene, for example 1,3-butadiene itself and of isoprene and copolymers of 1,3-butadiene with other monomers, for example styrene, acrylonitrile, isobutylene, and methyl methacrylate. The invention relates to diene rubbers, and the terms rubber and diene rubber are synonymous for the purposes of this invention.

Rubber stocks containing delayed-action accelerators can be used in the process of thisinvention. The stocks are fully accelerated in the absence of the inhibitor and may contain an amine to protect the rubber from degradation. The amine usually reduces processing safety, but the new vulcanizing systems are effective to prevent premature vulcanization in the presence thereof. More scorchy accelerators can also be used with an excellent degree of improvement. The improved vulcanizing method of this invention can be used advantageously to process stocks containing furnace carbon blacks as well as stocks containing other types of blacks and fillers used in rubber compounding. The invention is also applicable to gum stocks.

The data infra illustrate that a combination of an accelerator and an inhibitor of this invention is an improved rubber additive which allows significantly longer and safer processing time for rubber. Further,

the accelerator-inhibitor combinations of this invention may improve the modulus of a vulcanizate considerably. The storage stability of a rubber mixture containing an accelerator-inhibitor combination of this invention is improved compared to a rubber mixture containing an accelerator alone.

My invention is applicable to rubber mixes containing sulfur-vulcanizing agents, organic accelerators, and antidegradants. For the purposes of this invention, sulfur-vulcanizing agent means elemental sulfur or sulfurcontaining vulcanizing agent, for example, an amine disulfide, or a polymeric polysulfide. The invention is applicable to vulcanization accelerators of various classes. For example, rubber mixes containing the aromatic thiazole accelerators which include N-cyclohexyI-Z-benzothiazolesulfenamide, Z-mercaptobenzothiazole, N-tert-butyl-Z-benzothiazolesulfenamide, 2-benzothiazo1yl diethyldithiocarbamate, N, N- diisopropyl-2-benzothiazolesulfenamide, and 2(morpholinothio)benzoth iazole can be used. Thiazole accelerators other than aromatic can be used. Stocks containing accelerators, for example tetramethylthiuram disulfide, tetramethylthiuram monosulfide, aldehyde amine condensation products, and guanidine derivatives, are substantially improved using the method of my invention. Stocks containing mixtures of accelerators are substantially improved by using the method of my invention. Rubber mixes containing antidegradants, for example N-1,3-dimethylbutyl-N- phenyl-p-phenylenediamine, N,N'-bis( 1 ,4-dimethylpentyl)-p-phenylenediamine, N,N'-bis(2-octyl)-pphenylenediamine, and other phenylenediamines, ketone, ether, and hydroxy antidegradants and mixtures thereof, are substantially improved using the process of my invention.

PREFERRED EMBODIMENTS 3-Cyclohexylthio-3-azabicyclo[3.2.2]nonane prepared as follows:

Cyclohexyl sulfenylchloride (45.1 g., 0.25 mole) in 150 ml. of heptane is added dropwise in 15 minutes to a stirred solution of 3-azabicyclo[3.2.2]nonane (37.5 g., 0.3 mole) and triethylamine (30.4 g., 0.3 mole) in 500 ml. of ethyl ether at 5-l5C. The mixture is stirred 24 hours at 25-30C. 300 ml. of water is added and the mixture stirred an additional 15 minutes. The etherheptane layer is separated, washed with water until neutral, and dried over sodium sulfate. The ether and heptane are removed in vacuo at -90C. at 1-2 mm. Hg. The residue is filtered hot to remove one gram of solids. 51 Grams percent yield) of an amber liquid is recovered which solidifies upon standing. The product recrystallized from alcohol melts at 43-44C. Analysis of the 3-cyclohexy1thio-3-azabicyclo [3.2.2.]nonane gives 70.08% C, 10.69% H, 5.89% N and 13.32% S compared to 70.23% C, 10.53% H, 5.85% N and 13.39% S calculated for C H NS.

3-Cyclooctylthio-3-azabicyclo[3.2.2]nonane is an amber colored, viscous liquid which when analyzed gives 71.24% C, 10.76% H, 4.85% N and 11.87% S compared to 71.84% C, 10.93% H, 5.24% N and l S calculated for CmHggNS- 3-Cyclododecy1thio-3-azabicyclo[3.2.2]nonane is a cream colored solid which melts at 60 -62C. Analysis gives 4.31% N and 9.78% S compared to 4.33% N and 9.91% S calculated for C H NS.

The following data illustrate the use of the compounds as inhibitors for premature vulcanization. For the rubber stocks tested and described below, as illustrative of the invention, Mooney scorch times at 121C. are determined by means of a Mooney plastometer. The time in minutes (t required for the Mooney reading to rise 5 points above the minimum viscosity is recorded. Longer times are indicative of the activity of the inhibitor. Longer times on the Mooney scorch test indicate greater processing safety. Increases in scorch delay of the stock containing the premature vulcanization inhibitor over stock which contains no inhibitor is shown. Curing characteristics of the stocks are determined by the Monsanto Oscillating Disc Rheometer. All stocks are cured at 144C. to achieve optimum cure which is determined from Rheometer data. the time in minutes for a rise of 2 Rheometer units above the minimum reading, and is the time required to obtain a modulus 90 percent of the maximum. The difierence between these two times, t t,, is indicative of cure rate.

A natural rubber masterbatch is compounded as follows:

Parts by Weight Smoked sheets 100 ISAF carbon black 45 Zinc oxide 3 Stearic acid 2 Hydrocarbon processing aid 5 Total 155 Stocks are prepared by adding accelerator, antidegradant, sulfur and the prevulcanization inhibitors to the masterbatch Prevulcanization inhibitor is excluded from the control. The properties of the vulcanizates are shown in Table I.

3-Cyclooctylthio-3 azabicyclo[ 3.2.2c

nonane 0.5 S-Cyclododecylthioazabicylco[3.2.2]no

nane 0.5 Mooney Scorch at 121C. t., minutes 27.7 48.0 32.9 32.7 I: increase in scorch delay 73 l9 l8 Rheometer at 144C. 1, 8.2 10.2 8.5 8.5 t -t; 11.5 11.0 11.0 10.6 300% Modulus, psi 1650 1850 1800 1900 Ultimate tensile strength, psi 3720 4120 4190 4300 The accelerator-inhibitor combinations of this invention provide com sitions with improved storage stabihty. For examp e, thiazolesulfenamrde accelerators lose activity upon storage. However, combinations of accelerators and 0.05-50 percent of the stabilizer or inhibitors of this invention after storage show greater vulcanization effectiveness than equivalent portions of the combination if stored alone and combined immediately prior to use. Usually in compositions intended for use as prevulcanization inhibitors, the inhibitor will comprise 5 to percent of the composition by weight, and an organic vulcanization-accelerating agent will comprise 95 to 5 percent by weight of the composition. In general, the inhibitor-stabilizer will comprise 0.025 to 5 percent of the rubber.

Although the invention has been illustrated by typical examples, it is not limited thereto. Changes and modifications of the examples of the invention herein chosen for purposes of disclosure can be made which do not constitute departure from the spirit and scope of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A compound of the formula wherein n is from 2 to 9.

2. A compound of claim 1 wherein n is 3. 3. A compound of claim 1 wherein n is 5. 4. A compound of claim 1 wherein n is 9. 

2. A compound of claim 1 wherein n is
 3. 3. A compound of claim 1 wherein n is
 5. 4. A compound of claim 1 wherein n is
 9. 